To help improve mobility on congested local highways and streets, the Los Angeles County Board of Supervisors instituted the Countywide Traffic Signal Synchronization Program (TSSP). Since the TSSP's inception in 1988, the County, through its Department of Public Works (DPW) and with the technical and financial assistance of numerous cities, the State of California Department of Transportation, and the Los Angeles County Metropolitan Transportation Authority (MTA), has been implementing innovative, low-cost operational improvements to the network of traffic signals on the major streets throughout Los Angeles County. The typical TSSP project involves upgrading all the traffic signals along a route to keep the signals synchronized, placing vehicle detectors in the pavement to detect the presence of vehicles, coordinating the timing of the signals between successive intersections, and automatically adjusting the traffic signals to facilitate the movement of vehicles through the intersections.

The first phase of this Program was completed in September 1995. 39 routes and 780 signalized intersections along 220 miles of streets in 58 cities and unincorporated areas were improved at an estimated cost of $17 million. Estimates show that this Program has saved motorists, on an annual basis, 468 million in vehicle costs, 31.9 million travel hours, 38.6 million gallons of fuel, and 10,100 tons of pollutants to date. Travel times were reduced by as much as 24 to 29 percent. The second phase of this Program is on-going and involves 135 projects on 102 routes, consisting of 2,670 signalized intersections along nearly 610 miles.